Valuing Air Barriers

Without national or local codes or regulations to mandate well-sealed apartment buildings, selling the cost benefit of tight building practices is key.

Here is a piece of old news: Air leakage in apartment buildings is responsible for high energy bills,occupant complaints about drafts, and building envelope durability problems. Given that it is well known that apartment buildings tend to be leaky, the building performance community should be well on our way to eliminating the problem. In actual fact,we haven't progressed very far.What is surprising is that we know the types of problem that air leakage causes; we know how air leakage can be reduced with better design details, construction supervision, quality assurance, and testing—and yet it still doesn't happen. Studies undertaken by the organization I belong to, the Canada Mortgage and Housing Corporation (CMHC),have found that air leakage in apartment buildings can contribute to as much as 20% of the annual space-heating energy load. It also represents a substantial proportion of the peak space-heating load (see Figure 1). Not surprisingly, air leakage control also represents a substantial energy and cost savings opportunity, as highlighted in a couple of air leakage control projects monitored by CMHC in the 1990s (see “A Tale of Two Towers,”...